A tetravalent vaccine comprising hexon-chimeric adenoviruses elicits balanced protective immunity against human adenovirus types 3, 7, 14 and 55

Study on the Anti-Adenovirus Mechanism of Sargassum fusiforme

Human adenovirus (HAdV) has a worldwide distribution and remains a major pathogen that leads to infections of the respiratory tract. No specific treatments or vaccines are yet available for HAdV infection. Sargassum fusiforme, an edible seaweed, has attracted a lot of attention for its various bioactivities. S. fusiforme has been reported to exhibit antiviral activity. However, research studies about its anti-HAdV activity are few. In this research, we found that S. fusiforme had low cytotoxicity and possessed anti-human adenovirus type 7 (HAdV7) activity in vitro, and the most effective ingredient was alginate. The time of addition assay demonstrated inhibitory effects that were observed in all life stages of the virus. In addition, we observed that the antiviral activity of alginate against HAdV7 infection might be closely related to the endoplasmic reticulum stress (ERS) pathway. Taken together, these results suggest that S. fusiforme extracts have potential application in the prevention and treatment of HAdV infection.

A bivalent live-attenuated vaccine candidate elicits protective immunity against human adenovirus types 4 and 7

Human adenovirus types 4 (HAdV4) and 7 (HAdV7) often lead to severe respiratory diseases and occur epidemically in children, adults, immune deficiency patients, and other groups, leading to mild or severe symptoms and even death. However, no licensed adenovirus vaccine has been approved in the market for general use. E3 genes of adenovirus are generally considered nonessential for virulence and replication; however, a few studies have demonstrated that the products of these genes are also functional. In this study, most of the E3 genes were deleted, and two E3-deleted recombinant adenoviruses (ΔE3-rAdVs) were constructed as components of the vaccine. After E3 deletion, the replication efficiencies and cytopathogenicity of ΔE3-rAdVs were reduced, indicating that ΔE3-rAdVs were attenuated after E3 genes deletion. Furthermore, single immunization with live-attenuated bivalent vaccine candidate protects mice against challenge with wild-type human adenovirus types 4 and 7, respectively. Vaccinated mice demonstrated remarkably decreased viral loads in the lungs and less lung pathology compared to the control animals. Taken together, our study confirms the possibility of the two live-attenuated viruses as a vaccine for clinic use and illustrates a novel strategy for the construction of an adenovirus vaccine.

Molecular typing of human adenoviruses among hospitalized patients with respiratory tract infections in a tertiary Hospital in Guangzhou, China between 2017 and 2019

Background

Human Adenoviruses (HAdVs) cause a wide array of illnesses in all age groups. They particularly cause frequent morbidity among children. In China, human adenovirus types 3, 4, 7, 11, 14, 21, and 55 have caused at least seven outbreaks since 2000. However, limited studies are available regarding the epidemiological patterns and diversity of HAdVs types among hospitalized patients with respiratory tract infections (RTIs).

Methods

To understand the epidemiology and subtype distribution of HAdV infections associated with RTIs in China, nasal swab (NS) clinical samples were collected from 4129 patients in a Guangzhou hospital between August 2017 and October 2019. PCR, sequencing, and phylogenetic analysis were performed on these specimens to identify HAdV subtypes.

Results

HAdV was successfully sequenced in 99 (2.4%) of the 4129 NS specimens, with the highest HAdV prevalence (6.3%) found in children between the ages of 5 and 10 years. Among HAdV-positive specimens, the most prevalent genotypes identified were HAdV-B3 (55.6%) and HAdV-B7 (25.3%). The most common symptoms in the HAdV-infected patients were fever (100%), cough (80.8%), and rhinorrhea (71.8%). HAdV infections were detected throughout the year with a relatively higher prevalence in summer.

Conclusion

All ages suffer adenovirus infections, but young children are at the greatest risk. This study data demonstrates that at least three species of HAdVs (species B, C, and E) are circulating in Guangzhou City, China. As antiviral therapies and type-specific vaccines become available, such epidemiological data will be useful in guiding therapy and public health interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06412-0.

Ongoing outbreak of human adenovirus-associated acute respiratory illness in the Republic of Korea military, 2013 to 2018

BACKGROUND/AIMS

Human adenovirus type 55 (HAdV-55), an emerging epidemic strain, has caused several large outbreaks in the Korean military since 2014, and HAdV-associated acute respiratory illness (HAdV-ARI) has been continuously reported thereafter.

METHODS

To evaluate the epidemiologic characteristics of HAdV-ARI in the Korean military, we analyzed respiratory virus polymerase chain reaction (RV-PCR) results, pneumonia surveillance results, and severe HAdV cases from all 14 Korean military hospitals from January 2013 to May 2018 and compared these data with nationwide RV surveillance data for the civilian population.

RESULTS

A total of 14,630 RV-PCRs was performed at military hospitals. HAdV (45.4%) was the most frequently detected RV, followed by human rhinovirus (12.3%) and influenza virus (6.3%). The percentage of the military positive for HAdV was significantly greater than the percentage of civilians positive for HAdV throughout the study period, with a large outbreak occurring during the winter to spring of 2014 to 2015. The outbreak continued until the end of the study, and non-seasonal detections increased over time. The reported number of pneumonia patients also increased during the outbreak. Case fatality rate was 0.075% overall but 15.6% in patients with respiratory failure. The proportion of severe patients did not change significantly during the study period.

CONCLUSION

A large HAdV outbreak is currently ongoing in the Korean military, with a trend away from seasonality, and HAdV-55 is likely the predominant strain. Persistent efforts to control the outbreak, HAdV type-specific surveillance, and vaccine development are required.

Seroprevalence of Neutralizing Antibodies against Six Human Adenovirus Types Indicates the Low Level of Herd Immunity in Young Children from Guangzhou, China

Human adenoviruses (HAdVs) commonly cause many diseases such as respiratory diseases, gastroenteritis, cystitis worldwide. HAdV-3, -7, -4 and emergent HAdV-55 and HAdV-14 are the most important types causing severe respiratory diseases. There is no effective drug available for clinical treatment, and no vaccine available for the general population. Therefore, it is important to investigate the seroprevalence against HAdV for developing novel vaccines and vectors. In this study, we investigated the seroprevalence and titer levels of neutralizing antibodies (NAb) against HAdV-3, -4, -7, -14, -55, and -11 in total 278 healthy populations between 0 months and 49 years of age (228 children and 50 adults) from Guangzhou. In children under the age of 18 years, the seropositive rates were significantly increased against HAdV-3 at 12.07%, 33.96%, and 64.29% and against HAdV-7 at 0%, 18.87%, and 19.05% in age groups of 1–2, 3–5, and 6–17 years, respectively. The seroprevalence was very low (0% ~ 8.1%) for all other four types. In adults aged between 18 and 49 years, HAdV-3, -4, and -7 (> 50.00%) were the most common types, followed by HAdV-14 (38.00%), -55 (34.00%), and -11 (24.00%). Adults tended to have high NAb titers against HAdV-4 and -55. HAdV-55-seropositive donors tended to be HAdV-11- and HAdV-14-seropositive. These results indicated the low level of herd immunity against all six HAdV types in young children, and HAdV-14, -55, -11 in adults from Guangzhou City. Our findings demonstrate the importance of monitoring HAdV types and developing vaccines against HAdV for children and adults.

Genomic foundations of evolution and ocular pathogenesis in human adenovirus species D

Human adenovirus commonly causes infections of respiratory, gastrointestinal, genitourinary, and ocular surface mucosae. Although most adenovirus eye infections are mild and self-limited, specific viruses within human adenovirus species D are associated with epidemic keratoconjunctivitis (EKC), a severe and highly contagious ocular surface infection, which can lead to chronic and/or recurrent, visually disabling keratitis. In this review, we discuss the links between adenovirus ontogeny, genomics, immune responses, and corneal pathogenesis, for those viruses that cause EKC.

Development of a TaqMan-based real-time PCR for detecting duck adenovirus 3

Recently, a novel duck adenovirus (designated as duck adenovirus 3, DAdV-3) was discovered in Muscovy ducks, China. Here, we developed a TaqMan-based real-time PCR assay (qPCR) for the detection of DAdV-3 infection. After the optimization of the qPCR conditions, the lower limit of detection for DAdV-3 infection was 40.9 copies/μl. No cross-reactivity was observed with other duck-derived pathogens. Intra- and inter-assay variability was less than 2.30%. DAdV-3 was detected in embryos and newly hatched ducklings by qPCR assay, the findings provided evidence of possible vertical transmission of DAdV-3. The developed qPCR analysis showed high specificity, sensitivity, and reproducibility, thereby indicating that it can be used in future investigations on the pathogenesis and epidemiology of DAdV-3.